Usually hard physical vapor deposition (PVD) coatings such as nitrides, carbides or diamond-like coatings with hardness of 2000 HV and higher are used for increasing lifetime of moving parts as is shown in WO 2012/078151, US 2013/0086881, US 2013/0085088. While hard coatings protect a surface and increase its lifetime, they decrease the fatigue strength and increase the wear rate of a counterpart. Also, while degrading, the fractured parts of the hard coating become abrasive and hasten degradation [“Surface Coatings for Protection Against Wear”, B. G. Mellor, Woodhead Publishing Limited, 2006].
Solid lubricant films can be used as an alternative to the hard coatings. In the last years, the main attention was paid to a group of nanocomposites consisting of an amorphous carbon and various metals (Ti, Ta, Zr, Au, Cu, Ag, etc.) [“Relationship between mechanical properties and coefficient of friction of sputtered a-C/Cu composite thin films”, J. Musil et al., Diam. & Rel. Mat. 17 (2008) 1905-1911]. A copper-carbon nanocomposite coating exhibits high plasticity, low friction, high adhesive and cohesive properties and it attracts particular attention due to its low cost [“Phase composition and tribological properties of copper/carbon composite films”, W. Gulbinski et al., Surf. & Coat. Tech. 200 (2005) 2146-2151]. Copper-carbon nanocomposite possesses sponge-like developed structure consisting of copper precipitates encapsulated in a carbon matrix [“Co-sputtering C—Cu thin film synthesis: microstructural study of copper precipitates encapsulated into a carbon matrix”, T. Cabioch et al, Phil. Mag. B 79 (1999) 501-516]. The result is that such a coating exhibits good tribological properties and greatly increases the lifetime of the surfaces that experience sliding or rolling friction. The main disadvantage of a pure copper-carbon nanocomposite coating is its low hardness, which leads to a high wear rate and makes it insufficient for applications under heavy loads.